project1_report_revise.doc

POLITECNICO DI TORINO（AUTOMOTIVE ENGINEERING） Motor Vehicle Design Project 1 TEAM --- 21 (Li Bing,Liu Kai Nian,Wang Jian Gang,Li Rui Xin) 2009/2010  INDEX 1. COMPUTATION OF THE SLOPE OF THE FX-σ CURVE, SIDE SLIP STIFFNESS AND SELF-ALIGNMENT TORQUE STIFFNESS a. Slope in the origin of Fx-σ curve b. Side slip stiffness c. Self-alignment torque stiffness 2. TIRE NONLINEAR MODEL 3. EVALUATION OF THE INTERACTION OF TIRE-ROAD FORCES IN LONGITUDINAL AND LATERAL DIRECTION  1. Evaluation of the slope of the Fx-σ curve in the origin, of the side slip stiffness and of the self-alig nment torque stiffness. a. Slope in the origin of Fx-σ curve ??the maximum longitudinal force coefficient ?xp with a vertical force Fz equal to [2 4 6 8 10] kN; Fz(kN) 2 4 6 8 10 μxp 1.47 1.45 1.43 1.41 1.39 BCD(N) 897.92 2233.87 3723.43 5182.24 6497.87 ??the slope in the origin (BCD) of the Fx-??curve with a vertical force Fz equal to [2 4 6 8 10] kN;  Comment: In case of the maximum longitudinal force coefficient Uxp with respect to vertical load Fz,as the vertical load Fz increases from 2 to 10 KN linearly, the corresponding Uxp decreases slightly,from 1.470 to 1.395,drops about 5 percent,which indicates that if the vertical load Fz increases with a certain rate,the corresponding manximum longitudinal force also increases,with a very slightly reduced rate with repect to the former,or in other words,non-proposionally.That is the reason why Uxp decreases a little. In the second case,as the plot indicates that the product BCD(also denoted as the tangent ratio of Fx/Fz) would increase linearly if the vertical load increases with a certain rate.(only seen roughly from the plot,In reality is not strictly linear though.) 3) The difference between these two cases ploted by the above mentioned curves are that the former is used to discribe the behavio